Currently marketed lighters all have an even number of output terminals, each for supplying high voltage to a spark plug for lighting a burner on a cooking range. In the case of a cooking range with an odd number of burners, therefore, a lighter with the nearest number of even terminals must be used, and the extra terminal must be earthed by an earth wire to neutralize its action without impairing operation of the lighter.
This is due to known lighters comprising as the main component a transformer, the secondary winding of which is defined by a number of electrically separate coils, each supplying voltage at the opposite ends to two respective terminals.
When assembling the cooking range, an additional earth wire (in addition to the one prescribed by regulations) must therefore be used, thus increasing assembly cost, time, and difficulty (in view of the normally confined space involved). A certain amount of energy is also wasted by being earthed by a wire or various connections. This continuity between the secondary winding wire and earth may even prove damaging in the event of a loss of insulation between the primary and secondary wires (e.g. as a result of a damaged winding or insulation).
Generators with odd numbers of output terminals are also marketed, though, in actual fact, these are identical to the former, except that the extra output terminal is earthed by internal connection to the earth on the printed circuit of the lighter, or to the earth contact on the casing. The problem of energy waste therefore remains unsolved, and the advantage in terms of assembly is normally achieved at the expense of higher production cost.